The invention relates to corrugated containers which are used in handling, processing and shipment of fruit, such as bananas.
Bananas produce large quantities of heat during the ripening process due to respiration. The final quality of bananas is greatly influenced by pulp temperature of the fruit during ripening. Therefore, bananas must be kept refrigerated at a control temperature. The refrigeration process must have the capacity to be able to accurately control pulp temperature, or the quality of the fruit will deteriorate, requiring that the refrigeration system do the following: (1) completely remove the heat of respiration from the load, (2) absorb any heat that flows into the room through the walls or that is generated by mechanical equipment, and (3) enable pulp temperature to be reduced at a reasonable rate.
The optimum pulp temperature for maintaining freshness is 58.degree. F. For maximum product shelf life, only during the commercial ripening cycle may the temperature be allowed to rise slightly above this 58.degree. F. level. After the ripening cycle is complete, pulp temperature must be lowered back to 58.degree. F. If pulp temperature rises to a higher temperature, shelf life is reduced. Excessively high pulp temperatures can cause "cooked" fruit, i.e. fruit having soft pulp and tender peels that split and break at the neck. High temperatures may also delay the desired color change from green to yellow.
Temperatures below 56.degree. F. will result in the bananas becoming chilled. If the temperature of chilled bananas is brought up to normal, the bananas will ripen normally, but the color will appear dull and the quality will be perceived as low.
In order that the fruit arrive at the point of sale in marketable condition, it is imperative that the conditions, e.g. of temperature, to which the fruit is subjected during shipment and storage be carefully controlled and regulated. For example, bananas are typically packed in cardboard containers at the plantation where they were harvested in a very green, unripened state, and shipped via refrigerated ships which keep the bananas at a temperature between 56.degree. and 59.degree. F. Once a refrigerated ship dock, the banana containers are carefully unloaded and stacked on pallets in refrigerated trucks or rail cars. En route to a warehouse, the pulp temperature of the bananas is checked repeatedly to ensure that it meets a specified temperature upon arrival. When the trucks reach the warehouse, the banana containers are again unloaded and stacked on pallets in ripening rooms. As a part of the ripening process, it is imperative that the banana containers be stacked with the side and end walls spaced apart in a manner to provide channels between containers for flow of air and gas. Various methods used to stack the banana containers include a "three block pattern," a "four block open chimney pattern", and a "pyramid stack." Although banana containers typically include apertures to allow flow of gas and air through the container, a full pallet load of existing shipping containers does not provide for effective air flow, and it is necessary to place the containers in one of the above cooling pallet patterns or in another pattern which incorporates a chimney allowing heat to escape. This typically requires that the containers be restacked from the pallet to create a chimney to permit air flow, causing additional handling which results in bruising and scarring of the fruit. Furthermore, the chimney stacking of the containers is not efficient pallet usage, so the containers must be re-palletized after ripening, again resulting in additional bruising and scarring of the fruit.
Once the banana containers are stacked on pallets in the ripening room, the pulp temperature is permitted to increase to 60.degree.-62.degree., and then ethylene gas is introduced into the ripening room and circulated through the containers to reduce the time necessary for the bananas to ripen fully. After the gas is cleared from the ripening room, the pulp temperature of the bananas is reduced and held until the bananas are shipped for delivery to the marketplace.
The handling requirements for other fruits are similar. For example, respirating fruits, e.g. such as tomatoes, may be ripened by control of the atmosphere.
Most current banana cartons employed at present are full telescoping, half-slotted containers (HSC), including a lid and base of approximately equal depth, the lid telescopically fitting over the base to complete the container. Another form of container used for the handing and storage of fruit is formed on a die cut machine, with multi-panel score lines cut in a blank to make a corrugated design of carton referred to in the industry as a "die cut tray". Other designs in use require a stitch in the panels to maintain infolded panels of the tray in a set-up condition. Other containers used for handling and processing fruit are two-piece telescopic containers consisting of a full height base and telescopically fitting top of substantially equal height. The base and lid are provided with vent apertures, slots or the like to enable circulation of gas and air through the container wall, over the fruit.